Possible Clues:

• Duplicitous
• Devious
• Conniving, conspiratorial
• “Amberley excelled at chess — one mark, Watson, of a ____ mind” (Sir Arthur Conan Doyle)
• Join the choir embracing church leaders every Monday planning in secret
• Tell the police locally about 100 on the border taking part in a conspiracy
• Southern church perhaps involves ministry full of intrigue
• Slippery barman is on edge with gin cocktail
• Plotting secretly
• Planning secretly